Conventional burners generally include an air tube having a fuel supply conduit (or two for dual fuel) extending axially within the tube. Each fuel supply conduit is connected at one end to a fuel supply pump or gas manifold and terminates at the other end near the end of the air tube where the fuel is dispensed as an oil spray or gas. The fuel is mixed with the air which has been delivered by a motor powered blower. A burner-mounted ignition system is connected to an ignition apparatus that is located adjacent to the fuel nozzle near the exit end of the air tube where it ignites the fuel-air mixture.
Burners of these types employ various mechanisms for adjusting air flow. For example, an oil burner disclosed in U.S. Pat. No. 5,184,949 employs an air gate disposed downstream of the blower for controlling the flow through an air flow passage. This fails to disclose a mechanism to control the total flow while simultaneously controlling the pressure behind the flame retention head, which pressure is important for reliable ignition and flame stability.